Synthesis of new homooxacalixarene based anion receptors

Publicações

Bidentate Urea Derivatives of p-tert-Butyldihomooxacalix[4]arene: Neutral Receptors for Anion Complexation

Publication . Marcos, Paula M.; Teixeira, Filipa A.; Segurado, Manuel A. P.; Ascenso, José R.; Bernardino, Raul J.; Michel, Sylvia; Hubscher-Bruder, Véronique

Three new bidentate ureidodihomooxacalix[4]- arene derivatives (phenyl 5a, n-propyl 5b, and tert-butyl 5c) were synthesized in four steps from the parent compound ptert- butyldihomooxacalix[4]arene and obtained in the cone conformation, as shown by NMR studies. The binding ability of these neutral receptors toward spherical, linear, trigonal planar, and tetrahedrical anions was assessed by 1H NMR and UV-vis titrations. The structures and complexation energies of some complexes were also studied by DFT methods. The data showed that the association constants are strongly dependent on the nature of the substituent (aryl/alkyl) at the urea moiety. In general, for all the receptors, the association constants decrease with decrease of anion basicity. Ph-urea 5a is the best anion receptor, showing the strongest complexation for F- (log Kassoc = 3.10 in CDCl3) and also high binding affinity for the carboxylates AcO- and BzO-. Similar results were obtained by UV-vis studies and were also corroborated by DFT calculations.

2014-01-07Artigo científico

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Palavras-chave

Calixarenes, Receptors, Hydrogen bonds, Anions, Exact sciences ,Exact sciences/Chemical sciences

Entidade financiadora

Fundação para a Ciência e a Tecnologia, I.P.

Programa de financiamento

Concurso para Projectos de I&D em todos os Domínios Científicos - 2006

Número da atribuição

PTDC/QUI/69858/2006